The invention is directed to an antioxidant containing oxymethylene copolymer-molding composition in the thermoplastic processing.
In the thermoplastic processing of oxymethylene copolymer molding compositions, there are set free small amounts of formaldehyde. Thereby, it can be a matter of dissolved formaldehyde which gasses out of the melt and the hot molded parts or of formaldehyde which is formed by thermally splitting off. The use of special more economical processing methods is frequently possible only with increased exposure of the polymerizate melt to heat. With increasing exposure to heat, however, there is increased danger of damage to the product and therewith increased emission of formaldehyde. The setting free of formaldehyde is unpleasant in two aspects. It can lead to health problems of the service personnel and make necessary suction apparatuses and absorption plants for the protection of the environment. Furthermore, the formaldehyde emitted can also cause deposits on dies and through this damage the surface quality and the true dimensions of the molded pieces.
Therefore, there exists a pressing demand to reduce the formaldehyde emission in the thermoplastic processing of oxymethylene copolymer molding compositions. This demand is satisfied by the molding compositions of the invention.